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Патент USA US3094558

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United States Patent 0 ’ "ice
Patented June 18, 1963
relatively low temperature, such as 50-80“ C., and the
temperature thereafter gradually raised as the reaction
proceeds until a maximum of 120-150“ is reached. Simi
larly, the alkylene oxide is conveniently added progressive
ly during the reaction, the ?nal concentration being suit
Arthur E. Gurgiolo and Robert A. Newton, Lake Jackson,
Tex., assignors to The Dow Chemical Company, Mid
land, Mich., a corporation ‘of Delaware
N0 Drawing. Filed July 27, 1961, Ser. No. 127,139
12 Claims. (Cl. 260-461)
This invention relates to an improved process for pro 10
ducing phosphate esters of alkylene glycols and dialkylene
glycols and to the esters thus obtainable.
It is known to condense alkylene oxides with phosphoric
acid, thus to form phosphate esters wherein the phosphoric
ably about 1 to 10 moles of oxide per mole of phosphoric
acid used. The excess, if any, after the low acid num
ber shows that the reaction is complete, is readily remov
able by distillation.
The alkylene oxides useful in the process of the inven
tion include not only the alkylene oxides, such as ethylene
oxide, propylene oxide and the isomeric butylene oxides
but such oxides containing inert substituents, such as
epichlorohydrin, styrene oxide, glycidol and the ethers
acid is esteri?ed more or less completely with an alkylene 15 and esters of glycidol.
In general, the process of the invention consists es
glycol or a polyoxyalkylene glycol (see, for instance US.
sentially of dissolving the phosphoric acid and at least a
Patent 2,372,244). Another known method of making
part of the alkylene oxide in a suitable volume of the
such esters is by the reaction of a phosphorus halide with
solvent, heating the mixture at reaction temperature, with
the glycol or polyoxyalkylene glycol (see British Patent
653,353). ‘In these prior methods it has been found quite 20 or without concurrent addition of more oxide, until the
acid number of the mixture has fallen to a suitable low
di?icult to esterify all three of the hydroxyl groups of
value, thus indicating that all the hydrogens of the phos
phosphoric acid, the second and third such groups being
phoric acid have reacted with oxide, removing the excess
well known to be progressively less reactive than the ?rst.
oxide, if any, and thus obtaining the desired phosphate
In the method of the above US. patent, for instance, it
has been found that 6 to 7 moles of alkylene oxide must 25 ester as a residue.
The practice of the invention is further illustrated by the
be used per mole of phosphoric acid in order to produce
following examples:
a product having a satisfactorily low acid number. A
Example 1
similar di?iculty is encountered in the process of the .above
British patent in that it is difficult to react all the halogen
Into a 10-gallon reactor was charged 40 lb. of dioxane
in the phosphorus halide. Also, polymerization and 30 and 5 lb. of 97% H3PO4. The reactor and contents were
halogenation of the initial product are unavoidable.
heated to 80° C., after which 35 lb. of 1,2-propylene
It is an object of the present invention to provide im
oxide was added over a 20-minute period, the temperature
proved methods for condensing phosphoric acid with
being maintained at 230-1000 C. The mixture was di
gested 4 hours at 80°, after which the excess propylene
mum consumption of .alkylene oxide; i.e., not more than
oxide and the dioxane were distilled out. The residue was
alkylene oxides whereby tri-esters are formed with mini
about 5 moles per mole of phosphoric acid, and having
an almost colorless oil containing 9.5% phosphorus and
a low acid number, preferably below 5.
13.9% OH and having an acid number of less than 0.1
According to the invention, phosphoric acid is con
and a hydroxyl equivalent weight of 122.. From the
densed with an alkylene oxide in an inert organic solvent.
40 phosphorus analysis, and assuming one atom of phos
The use of a solvent greatly facilitates the reaction and
phorus per molecule, it can be calculated that only 3.9
results in the production of a product having the above
moles of oxide reacted with each mole of phosphoric
desired characteristics.
acid. Thus, the product apparently consisted. of a mixture
Any solvent that dissolves the reactants and is inert to
of tris(2-hydroxypropyl) phosphate and bis(2-hydroxy
them under the conditions of the process can be used. 45 propyl) 2-(2-hydroxypropoxy) propyl phosphate.
Preferably it should be su?iciently volatile to be readily
Example 2
distillable. Suitable solvents include ethers, such as di
By use of the equipment and procedure described in
ethyl and dibutyl ethers and dioxane; alkyl nitriles, such
as acetonitrile and butyronitrile; the polyhalogenated ali
Example 1, 35 lb. of ethylene oxide were added over a
phatic hydrocarbons, such as chloroform, methylchloro 50 25 minute period to a solution of 5 lb. of 97% phos
form and trichloroethylene; alkyl phosphates and phos
phoric acid in 40 lb. of dioxane while the temperature of
phonates, such as triethyl phosphate, dimethyl butyl
phosphonate, tributyl phosphate and diethyl phenylphos
the mixture was maintained at 80-l05° C.
The product thus obtained was an almost colorless oil
phonate; dialkyl sulfoxides, such as dimethyl or d-iethyl
containing 15.7% OH and 9.5% phosphorus and having
sulfoxide, mixtures of the foregoing solvents, and the like. 55 an acid number of 1.0. The pH of a 25% solution in
Of these, the preferred solvents are dioxane, acetonitrile,
methanol-water (10:1 moles) was 3.7. These analyses
triethyl phosphate and chloroform.
correspond to a phosphate ester containing 5.1 oxyethylene
The amount of solvent may be varied Widely, as little
as one volume per volume of phosphoric acid being bene
Example 3
?cial. Larger amounts up to ?fty volumes or more give 60
Into a 5-liter reactor was placed 196 g. (2.0 moles)
improved results and even larger amounts may give some
of 100% H3PO4 and 800 g. of dioxane. The mixture
further improvement. Practical considerations of reactor
was heated to 75° C. after which 1040 g. (11.25 moles)
capacity and recovery costs usually limit the amount of
of epichlorohydrin were gradually added while the tem
solvent to not more than about ?fty volumes, the preferred
was maintained at 75-80“ After the mixture
amount being usually about 5 to 30 volumes per volume 65
had digested 30 minutes at 75° C. it was allowed to stand
of phosphoric acid.
18 hours at room temperature. Then the solvent and
In the reaction of phosphoric acid with an alkylene
unreacted epichlorohydrin were removed by vacuum dis
oxide, the initial rate of reaction is high, the rate decreas
tillation, the ?nal stage being at 90° C. and 5 mm. pres
ing rapidly after about two molar equivalents of the oxide
sure for 72 hours. There was thus obtained 970 g. of a
have been reacted. For this reason it may be advantageous
to raise the reaction temperature and/or the concentra 70 light yellow, viscous syrup having an acid number of
tion of alkylene oxide after the initial stage of the reaction
is completed. The reaction is conveniently started at a
0.25. Analysis showed it contained 5.6 epichlorohydrin
moieties per atom of phosphorus.
Example 4
We claim:
was maintained at 50° C., 513 g. (4.5 moles) of alkyl
glycidyl ether over a 30-minute period, after which the
mixture was digested 1 hour at 80° C. The solvent and
unreacted glycidyl ether were then distilled at 80° C.
(.pot temperature) and 5 mm. pressure to leave 520 g. .
of an oily product having 11.6% OH and 7.05% phos
1. In the process of producing phosphate esters by
the condensation of phosphoric acid with an alkylene
oxide, the improvement of conducting said condensation
in an inert organic solvent.
Into a 2-liter reactor was put 98 g. (1 mole) of 100%
H3PO4 and 392 g. of dioxane. While the temperature
2. The process de?ned in‘ claim 1 wherein the solvent
is dioxane.
3. The process de?ned in claim 1 wherein the solvent
is an alkyl nitrile.
4. The process de?ned in claim 1 wherein the solvent
While in the above examples dioxane was used as the
is a polyhalogenated aliphatic hydrocarbon.
5. The process de?ned in claim
is an alkyl phosphate.
6. The process de?ned in claim
15 is a dialkyl sulfoxide.
form, diethyl ether and Xylene.
7. The process de?ned’ in claim
Good results have been obtained with phosphoric acid
is acetonitrile.
varying from 85% to 102% nominal H3PO4.
8. The process de?ned in claim
In other experiments similar to that described above
is chloroform.
using various oxides and solvents as set forth herein
9.- The process de?ned in claim
about 3.5 to 5 moles of oxide were required to reduce 20
solvent, equally good results were obtained when aceto;
nitrile or triethyl phosphate were used. Slightly poorer,
though satisfactory, results were obtained with chloro
1 wherein the solvent
1 wherein the solvent
1 wherein the solvent
1 wherein the solvent
1 wherein the solvent
the acid number of the product to 1.0 or less. Hydroxy
is t-riethyl phosphate.
equivalent weights as loW as 108 were sometimes ob
10. The process de?ned in claim 1 wherein the solvent
is used in an amount at least equal in volume to the
tained in such products made with propylene oxide.
Ethylene oxide reacts more vigorously than propylene
phosphoric acid.
11. A mixture of hydroxyalkyl phosphate esters con
taining an- average of about 3.5 to 5 oxyalkyl groups
per molecule and having an acid number of not more
than about '5.
less reactive and require higher temperatures, longer
12. The composition de?ned in claim 11 wherein the
times or higher concentrations of oxide to produce prod
30 oxyalkyl groups are oxypropyl groups.
ucts having acid numbers below 5.
oxide and hence can be used at lower temperatures and 25
with shorter reaction times. On the other hand, epic
chlorohydrin, the butylene oxides and styrene oxide are
The new compounds of the invention are useful for
the same purpose as the related materials described in
the patents cited above. They are particularly useful as
polyol reactants in the production of ?re~resistant ure
thane resins, as is more fully described in the copending 35
application of Presley and Davis, entitled “Self-Extin
guishing Polyurethane Resin,” ?led July 25, 1961, Serial
No. 126,526.
References Cited in the ?le of this patent
Adams et al __________ __ Mar. 27,
Smith ________________ __ Apr. 8,
Haas et al. ____________ __ July 8,
Lanham __________ _2___ Oct. 20,
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